Year	Percent
1966	4.60805
1967	1.3504
1968	0.89295
1969	1.47067
1970	2.20025
1971	2.44852
1972	2.51119
1973	11.49723
1974	11.23058
1975	10.39019
1976	12.46811
1977	9.92629
1978	10.97566
1979	22.32219
1980	18.03013
1981	1.18806
1982	9.1673
1983	8.29323
1984	11.15999
1985	9.03761
1986	12.78236
1987	31.13816
1988	13.65302
1989	18.53729
1990	18.44061
1991	14.47857
1992	19.73342
1993	8.42911
1994	8.44887
1995	11.39973
1996	7.10767
1997	9.87756
1998	3.89227
1999	0.86995
2000	4.93288
2001	1.8677
2002	3.18548
2003	6.7787
2004	11.67219
2005	6.20539
2006	7.34986
2007	12.59317
2008	12.20259
2009	11.18528
2010	10.10909
2011	11.6465
2012	19.49526
2013	8.71267
2014	11.24762
2015	9.93089
2016	6.24566
2017	22.93255